South Africa and Australia on high alert over deadly listeriosis outbreaks

Brenda Lau, Zayani Bhatt, 09 Mar 2018

The sources of the Listeriosis outbreaks in South Africa and Australia have been identified. Consumers are warned to take caution against eating raw foods and vegetables.

South Africa has finally traced the sources of the ‘world’s worst outbreak’ of Listeriosis, which killed 180 people over the past year. A factory operated by the company Enterprise Foods in Polokwane in the Limpopo province has been identified. More specifically, a ready-to-eat sausage known as polony is the main culprit, said Health Minister Aaron Motsoaledi.

More than 16 environmental samples from the factory tested positive for the ST 6 strain of Listeria – a particularly virulent strain, which has so far infected almost 1,000 people.

"In our constant search for the source of the outbreak and the treatment of people who are affected, a team from the National Institute for Communicable Diseases (NICD) has interviewed 109 ill people to obtain details about foods they had eaten in the month before falling ill. Ninety-three (85%) reported eating ready to eat (RTE) processed meat products, of which polony was the most common, followed by viennas/sausages, and then other ‘cold meats’," said Motsoaledi.

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Separate outbreak in Australia

Across the ocean, four people in Australia have died after eating Cantaloupe melons – or more fondly known as rock melons – contaminated with Listeria.

“There have been two deaths in New South Wales and two in Victoria,” NSW Health said in an update, adding that the two new cases took the total affected nationally to 17.

The Australian outbreak began in January this year and rock melons have now been withdrawn from supermarket shelves across the country.

Four out of 17 infected individuals have died due to the listeria outbreak involving rock melons in Australia. Photo credit: Techly

Australia has also been quick to identify the source to a farm near the city of Griffith in New South Wales in Australia. According to Vicky Sheppeard, Director of Communicable Diseases Branch for the New South Wales Health authority, "people vulnerable to listeriosis should discard any rock melon purchased before 1 March."

“Typically, around one-third of people who fall ill with listeriosis die every year. Most of the cases are never related to an outbreak like this one we’re seeing with the rock melon contamination,” she added.

Singapore has also recalled two consignments of rock melons from the affected farm in Australia that were available for sale from 12 February to 2 March. The country has also suspended import of such rock melons for the time being.

High-risk individuals warned to take most caution

Consumers have been warned against the extremely hardy salt-resistant bacterium that can grow at refrigeration temperatures and spread easily.

High-risk individuals such as pregnant women, babies, elderly and those with weakened immune systems are especially warned to prevent eating those foods as the bacterium responsible, Listeria monocytogenes, can be fatal.

The incubation period for the infection is anywhere between one and 70 days. Therefore, it may take a long time before knowing if an infection has spread pandemically– although this is unlikely, as sources would have been identified and halted from further distribution of food. Most healthy individuals exposed to it do not show symptoms.

Doctors have also been advised to look out for patients with listeriosis, and to provide antibiotics and supportive measures such as intravenous fluids for dehydration. Particularly in pregnant women, early-delivery of antibiotics is crucial to prevent infection of the foetus. Maintaining regular basic hygiene is also advised to prevent the spread of the infection. MIMS